How does a portable appliance get even more useful?

Suppose an individual born in the U.S. lives the average life expectancy (78.4 years today). In that case, they can expect numerous iterations of technological innovations and improvements throughout their lifetime, especially for healthcare products and systems. Looking back, an item like the Holter monitor (developed in 1947 and released for commercial production in 1962) provides an excellent historical example.

Holter monitor progress

To provide ambulatory measurements of the heart, the first Holter monitor was developed in 1947. It weighed 84 pounds and utilized a tape recorder for data collection. While extremely cumbersome, it did allow the wearer motion rather than lying motionless on a table that previous electrocardiograms (ECGs or EKGs) required. Working on the principle of a galvanometer, similar to an EKG, the Holter monitor, with its attached electrodes, measures the tiny electrical currents generated by the heart and converts them into a readable voltage format to identify normal versus abnormal heart rhythms.

Figure 1. Monitoring a user’s heart activity for 24-48 hours requires electrodes attached to skin and a portable measuring and recording device. (Image: Mayo Clinic)

With the invention of transistors, Holter monitors became portable, and the first commercial devices were offered for sale in 1962 with the intended use of storing up to 48 hours of data. The conversion from analog to digital technology and the availability of Flash memory enabled further size and weight reduction, see Figure 1. With electrodes attached to the patient’s chest, the signals were captured by a device that was typically the size of a small camera and worn on a strap around the patient’s shoulder, neck, or waist.

Unlike a smartphone, where once you have one, you get a newer version every few years, the typical need for wearing a Holter monitor can mean several years or even decades between usage. As a result, several key technological advancements (such as solid-state memory and more) can occur between these periods and offer pleasant surprises to the patient. Today’s use of the latest technologies allows a 40 x 49 x 10 mm (1.6 x 1.9 x 0.39 in) sensor weighing 16 g (0.56 oz) to record up to 14 days of data while worn on a patient’s chest, see Figure 2.

Figure 2. A lightweight, ePatch Holter monitor (a – front side and b – backside) with four integral electrodes easily attaches to the wearer’s chest to make measurements for up to 14 days. (Image: Philips)

The added recording time and storage capability (2 GB internal storage) provide additional data for a more thorough diagnosis and treatment of various types of arrhythmias. The small device also provides patients with options for diagnosis. With its ability to obtain and store up to 14 days of continuous extended monitoring, at the end of the targeted period (or sooner if an abnormality occurs), the patient can simply mail the monitor back to the company in its provided package for analysis, with the results sent to the doctor. Alternatively, they can have the doctor download data from their practice/hospital for faster results. In either case, no battery changes are required by the patient.

Unlike earlier bulky versions designed for up to two days of data collection, a patient wearing an ePatch Holter monitor for 14 days can expect to shower during its use. For this to occur, the monitor is water-resistant and has an International Electrotechnical Commission (IEC) standard rating for ingress protection (IP) of IPX4 when connected to a compatible patch/electrode.

Getting better all the time

Today’s Holter monitor is smaller, lighter, and interferes less with the wearer’s daily activities. At the same time, it is much more capable of providing improved data (functionality) to analysts. In that regard, it is very similar to just about every other portable product.